A variety of biochemical parameters will be tested to determine the extent to which they may provide useful reflections of animal exposure to neurotoxic agents and/or of animal behavioral modification by various drugs. Several enzymes will be used to provide markers for plasma membranal-, mitochondrial-, endoplasmic reticulum-, and nuclear function, as well as several aspects of energy and neurotransmitter metabolism. It is anticipated that a general biochemical screening technique will evolve to permit prediction of neurotoxicological consequences of animal exposure to toxic agents of environmental interest.